Influence of block length on crystallization kinetics and melting behavior of poly(butylene/thiodiethylene succinate) block copolymers

The melting behavior and the crystallization kinetics of block poly(butylene/thiodiethylene succinate) copolymers (PBSPTDGS) with identical chemical composition (i.e., BS:TDGS = 50:50 mol %) were investigated by means of differential scanning calorimetry. Multiple endotherms were evidenced in PBSPTDGS samples, because of melting and recrystallization processes, similar to poly(butylene succinate) (PBS). By applying the Hoffman-Weeks' method, the of the copolymers was derived. The isothermal crystallization kinetics was analyzed according to the Avrami's treatment. The copolymer with long PBS blocks (PBSPTDGS15) is characterized by a very similar behavior with respect to pure PBS, indicating that PBS macromolecular folding is not affected by the presence of noncrystallizable thiodiethylene succinate blocks. In all the other cases, the overall crystallization rate was found to decrease as the block length is decreased, even though the work of chain folding, derived on the basis of Hoffman-Lauritzen nucleation theory, also decreased with the block length.